A tale of two tests: why Energy Star LED light bulbs are a rare breed

Just over a week ago we reported that Philips' 22 W LED light bulb, designed as a like-for-like replacement of a 100-W incandescent light bulb, was the first LED bulb of its type to receive the stamp of approval from Energy Star. But looking at the Energy Star requirements reported by Philips in its press release, it seemed a little strange that Philips' product is the only one to have been certified – given that products long on the market appear, at face value, to meet those requirements. Since then, Gizmag has spoken to LED light bulb makers Switch Lighting and other industry players to find out why they're apparently playing catch-up.

"Those who do not remember the past …"

It turns out the reason is simple, but has a little bit of back-story attached. Unlike Energy Star certification for other types of appliances, an Energy Star-certified LED light bulb signifies reliability and performance as well as energy-saving performance. The reason for the difference is down to the problems faced by ordinary people when compact fluorescent bulbs first appeared.

"Originally, the Department of Energy was very concerned about what happened with compact fluorescent lighting when it first entered the market in that there were all kinds of variations of quality, reliability and performance," Gary Rosenfield, EVP of Marketing & National Accounts at Switch Lighting told Gizmag. (Though the lighting aspects of Energy Star now fall under the jurisdiction of the Environmental Protection Agency, when it came to specifying Energy Star criteria for LED products, it was the DoE.)

Compact fluorescent light bulbs are often criticized for being dim and slow to warm up (Photo: Mathew Bajoras)

The result has been something of a minor backlash against compact fluorescent lighting, though in reality this was more down to the shortcomings of individual products and the misleading ways in which they were sometimes sold. The DoE was keen to avoid a repeat performance when LEDs arrived, since LED products also vary enormously in quality. The relevant tests, devised by the Illuminating Engineering Society, are known as IES LM-79 and IES LM-80. A manufacturer that wants to apply for Energy Star certification must first pay an approved independent laboratory to carry out the tests on its behalf. With the results in hand, the manufacturer can then apply to the EPA (provided they're up to scratch, that is).

There is no fee for applying for Energy Star certification, nor for using the label. In fact the tests in themselves do not specify pass or fail results, but instead simply quantify performance and lifespan. It's the EPA that decides the benchmarks. Light output depends on the bulb's spec, but is a minimum of 1,600 lumens for bulbs purporting equivalence to a 100-W incandescent bulb. Among the other criteria are color rendering index of at least 80, and a rated life of at least 25,000 hours – more on that in a moment.

"The LM-79 is basically the test that defines the photometrics, in other words that defines what the light performance is," Rosenfield said. LM-79 quantifies light output and distribution, as well as electrical power, allowing the calculation of the all-important efficacy in lumens/watts. It also identifies the light's color characteristics, such as its appearance, and its ability to render colors accurately.

"That's a fairly short test to run," Rosenfield explained. "It's done with spheres in independent labs. You put the product into these spheres, very expensive test equipment that basically encloses the entire fixture, and it tests all those variables." Easy peasy.

An Integrating or Ulbricht sphere used for photometric testing of lamps and light fittings (Photo: Gamma Scientific)

Ageism

"The other test […] is purely a life test," he added. "And in our category that test is run for 6,000 hours, so it's effectively nine straight months of testing." Life test is a useful if loose euphemism for what the test actually measures, which is lumen depreciation: the extent to which the lamp's light output falls over time.

"All LED lights at some point are going to start losing the amount of lumens that come out of the light," Rosenfield said. "The industry has set a number, called L70, which basically represents 70 percent of the original light output, as the end of life for an LED." So, the industry defines an LED light bulb as dead when its output falls to 70 percent of what it was to begin with.

The problem, Rosenfield explained, is that LED light bulbs haven't been around long enough for the industry to have a good understanding of how their performance degrades over time. Instead an algorithm is used which, after 6,000 hours of testing, projects the number of hours remaining before the LED will reach L70. The 25,000-hour rated life of Switch's and other LED products has not been tested in full because doing so would take nearly three years. Instead this number is a projection based on the algorithm used. Even so, it's still a test that takes a significant amount of time. Depreciation, by the way, is non-linear, and light output can at times increase as well as fall away, Rosenfield explained.

There is a semi-shortcut, though. LED light bulbs are effectively electronics packages in which the LEDs are but one type of component. Being solid state lighting products themselves, the LEDs are eligible for testing under IES LM-80. If Cree, one of the LED manufacturers Switch has used for its bulbs, has its LEDs tested to 6,000 hours, Switch doesn't have to repeat the entire test. Switch's product can instead undergo a 3,000-hour (4.5-month) test to check that depreciation follows the expected pattern. "It's still an advantage to test for the entire 6,000 hours because we may be able to run longer than what the LEDs actually are claiming," Rosenfield said.

Quality control

Though LEDs may not generate heat to the extent of other light sources, they are very sensitive

to heat, so equally, just as a well-designed light bulb might extend an LED's longevity, might a poorly designed one compromise it? "I think that many companies fall out of the Energy Star qualification process because of that, because they don't have sufficient thermal management which is one of our big advantages," Rosenfield said, alluding to the LQD liquid cooling system employed in Switch's bulbs.

"Also companies fall out because they don't have the full light distribution required. For example, with an 'A lamp,' you have to have, to get the full Energy Star standard, 170 degrees of radial flux or light distribution all around the product at generally the same intensity all the way around," he added.

To pass the Energy Star benchmarks, Rosenfield concludes, products must perform robustly as well as demonstrate long life. He also explained that the EPA will pick up Energy Star-certified products in the market place to ensure that their performance matches what was certified – that the products are what they're being sold as, effectively.

The floodgates open?

But why is Philips' product the only "100-W equivalent" to have been certified? "They won't necessarily be the only one, because it's just a matter of when companies are able to start their testing," Rosenfield said. "The longest lead time of this whole process is the four and a half months initially for the LM-80 testing for at least a half the full test […] assuming you're working with an LED manufacturer that has already done their testing."

Are Switch products going to be certified in the near future? "As a matter of fact we'll shortly be announcing the first set of our products that will be Energy Star qualified," said Rosenfield. "We're within days of that."

Though Switch has had products on the market for some time, it's worth bearing in mind that Switch is a start-up company whereas Philips is one of the world's largest lighting manufacturers – not to mention one which manufacturers its own LEDs.

Osram Sylvania is another company with apparently eligible products. We asked it if Energy Star certification was on the cards. "The EnergyStar qualification is a very rigorous test with tight parameters," a spokesperson told Gizmag. "Some of the screw-based LED bulbs need to be tested for at least 6,000 hours (for example) and this can take up to nine months – which is why some of our bulbs have not been qualified yet."

Though we also reached out to GE about its LED products, they declined to respond.

Official line

In an email to Gizmag, an EPA spokesperson confirmed the certification process. "To earn the label, the manufacturer of the product must be an Energy Star partner and obtain third-party certification of the product based on testing in an EPA-recognized lab," the EPA said. "The requirements for LED bulbs address efficiency as well as a number of performance related metrics such as light distribution, durability, lumen maintenance and color quality (both initially and over time). Higher lumen products are eligible for certification, as long as they meet all the requirements and complete all the necessary testing."

It sounds as if a number of Energy Star LED products, 100-W equivalent A-lamps and otherwise, are headed for the market. This can only be a good thing. For LED products, Energy Star has set robust guidelines that should ensure that an Energy Star bulb is of high quality. Provided consumers know what to look for, perhaps LED can avoid the demonization that befell compact fluorescents.

How do you measure the life of a light source that could last decades? (Photo: <a href="http://www.shutterstock.com/pic-125252342/stock-photo--incandescent-lamp-was-replaced-by-energy-efficient-led-lamp-concept.html" target="_blank">Shutterstock</a>)

Compact fluorescent light bulbs are often criticized for being dim and slow to warm up (Photo: <a href="http://www.flickr.com/photos/19634988@N07/3522802579/" target="_blank">Mathew Bajoras</a>)

An Integrating or Ulbricht sphere used for photometric testing of lamps and light fittings (Photo: Gamma Scientific)

Switch Lighting's 60-W incandescent-replacement LED light bulb is filled with liquid silicone to draw heat away from the LEDs